Transport protocols and bulk file transfer

[stanislav shalunov <>]

Lisong Xu 
<>
 writes:

> 1) In addition to SABUL and SOBAS, maybe we should also mention
> another 'well-known' protocol TCP-westwood, which estimates the
> available bandwidth based on the delay information of acks, and then
> sets slow_start_ssthreshold accordingly.
> http://www.cs.ucla.edu/NRL/hpi/tcpw/

Right.  I won't be able to do that for -04.  Put on the to-do list.

> 2) About the time precision of bandwidth estimation and the
> delay-based protocols. I understand that bandwidth estimation may
> benefit from a high precision. But I am not sure why
> bandwidth-estimation require higher time precision than delay-based
> protocols, since both of them are based on the delay changes which
> are "on the same order of magnitude as the serialization delay at
> the bottleneck".

Suppose that we have a way to measure delay with an accuracy of 1ms
(after filtering and whatever statistical techniques are to be used).
It would seem like bandwidth-estimation techniques would not find that
very useful.  At the same time, this should be usable to drive the
target queue size to, say, 5ms, shouldn't it?

-- 
Stanislav Shalunov              http://www.internet2.edu/~shalunov/

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